1. Field of the Invention
The present invention relates to bipyrrolinonylidene-type compounds which are useful as colorants such as dyes and pigments, and relates to methods of producing the same.
2. Description of Related Art
A method of producing bipyrrolinonylidene represented by the formula (b): 
by air-oxidizing pyrrolinone represented by the formula (a): 
is disclosed (see Liebigs Ann. Chem., 702, 112-130 (1967)).
However, the yield in the above method is low, such as 10 to 15%, and the method is not suitable for large-scale industrial production of bipyrrolinonylidene.
Also, it was difficult to employ bipyrrolinonylidene represented by the formula (b) as dyes and pigments, or other organic chemical products or intermediates thereof because of its poor solubility in water and organic solvents.
An object of the present invention is to provide bipyrrolinonylidene-type compounds which are useful as colorants such as dyes and pigments, or other organic chemical products or intermediates thereof, and also provides a method of producing the bipyrrolinonylidene-type compound, which is suitable for large-scale industrial production with high yield.
The present inventors have found that a bipyrrolinonylidene-type compound, which develops a vivid navy blue color and is soluble in various organic solvents, can be produced with high yield by air-oxidizing a pyrrolinone compound using a specific catalyst, and thus the present invention has been completed.
To achieve the above object, the present invention provides a bipyrrolinonylidene-type compound represented by the general formula (1): 
wherein Ar1 and Ar2 each independently represents an aryl group, and R1 and R2 each independently represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 18 carbon atoms, or an aryl group.
To achieve the above object, the present invention also provides a method of producing a bipyrrolinonylidene-type compound represented by the general formula (4): 
wherein Ar3 represents an aryl group, and R represents a hydrogen atom, a halogen atom, a cyano group, a hydroxyl group, an alkyl group, an alkoxyl group, an amino group, an alkylamino group, a cycloalkyl group, a cycloalkyloxy group, an aryl group, an alkoxycarbonyl group, a cycloalkyloxycarbonyl group, a carbamoyl group, a nitro group, a carboxyl group or a sulfonic acid group, which comprises oxidizing a pyrrolinone-type compound represented by the general formula (3): 
wherein Ar3 represents an aryl group, and R represents a hydrogen atom, a halogen atom, a cyano group, a hydroxyl group, an alkyl group, an alkoxyl group, an amino group, an alkylamino group, a cycloalkyl group, a cycloalkyloxy group, an aryl group, an alkoxycarbonyl group, a cycloalkyloxycarbonyl group, a carbamoyl group, a nitro group, a carboxyl group or a sulfonic acid group in the presence of an anthraquinone-type catalyst.
The bipyrrolinonylidenedicarboxylic acid-type compound represented by the general formula (1) of the present invention can be used as a dye, as it is, because it develops a vivid navy blue color, or a metal salt of bipyrrolinonylidenedicarboxylic acid can be used as a pigment.
According to the method of the present invention, the bipyrrolinonylidene-type compound represented by the general formula (4) can be produced by a simple method of air-oxidizing a pyrrolinone compound in the presence of an anthraquinone-type catalyst. The bipyrrolinonylidene-type compound represented by the general formula (4) obtained by the method of the present invention is soluble in various solvents as compared with conventionally known bipyrrolinonylidene and is also useful as dyes and pigments, or other organic chemical products or intermediates thereof because it has a carboxyl group or an ester bond.
The present invention will now be described.
In the bipyrrolinonylidene-type compound represented by the general formula (1) used in the present invention, Ar1 and Ar2 each independently represents an aryl group. Examples of the aryl group include aromatic ring groups such as a phenyl group, naphthalene group, anthracene group, phenanthrene group, pyrene group or biphenyl group; and aromatic hetero ring groups such as a pyrrole group, pyrazole group, imidazole group, pyridine group, pyrimidine group, pyrazine group, indole group, quinoline group, carbazole group, furan group or thiazole group.
Also these aromatic rings may have substituents. Examples of the substituents include a hydrogen atom, halogen atom, cyano group, hydroxyl group, alkyl group, amino group, alkylamino group, alkoxyl group, aryl group, alkoxycarbonyl group, carbamoyl group, nitro group, sulfonic acid group and sulfonate group. Among these substituents, a halogen atom or sulfonic acid group is preferred. When the substituent is a halogen, the bipyrrolinonylidenedicarboxylic acid derivative (A) tends to exhibit higher chemical stability. When the substituent is a sulfonic acid group or a sulfonic acid metal salt group, the bipyrrolinonylidenedicarboxylic acid derivative (A) tends to exhibit higher solubility in water or organic solvents.
When the aromatic ring is substituted with plural halogen atoms, halogen atoms may be the same or different. When the halogen atom is a chlorine atom or a bromine atom, the bipyrrolinonylidenedicarboxylic acid derivative (A) tends to exhibit higher chemical stability and, therefore, it is preferred.
In the general formula (1), R1 and R2 each independently represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 18 carbon atoms, or an aryl group. It is preferred that R1 and R2 each independently represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. Examples of the alkyl group having 1 to 18 carbon atoms include alkyl groups such as a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group or n-octadecyl group; and cycloalkyl groups such as a cyclohexyl group. It is preferred that the bipyrrolinonylidene-type compound represented by the general formula (1) tends to exhibit higher heat stability when R1 and R2 each independently represents an alkyl group having 1 to 8 carbon atoms.
Among the bipyrrolinonylidene-type compounds represented by the general formula (1), a bipyrrolinonylidene-type compound represented by the general formula (2): 
wherein X1, X2, X3, X4, X6, X7, X8, X9 and X10 each independently represents a hydrogen atom, a halogen atom, a cyano group, a hydroxyl group, an alkyl group, an amino group, an alkylamino group, an alkoxyl group, an aryl group, an alkoxycarbonyl group, a cycloalkyloxycarbonyl group, a carbamoyl group, a nitro group, a sulfonic acid group or a sulfonate group, and R1 and R2 each independently represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 18 carbon atoms, or an aryl group is preferred.
The bipyrrolinonylidene-type compound represented by the general formula (1) used in the present invention has high solubility in water or organic solvents because it has a carboxyl group or an ester bond in a molecule, and also the bipyrrolinonylidene-type compound can be used as a dye, as it is, because it develops a blue to violet color hue. Among the compounds represented by the general formula (1), a metal salt of a bipyrrolinonylidene-type compound in which R1 and R2 are hydrogen atoms can be used as a pigment because it is insoluble in water or organic solvents.
Among the bipyrrolinonylidene-type compounds used in the present invention, a bipyrrolinonylidene-type compound in which R1 and R2 are hydrogen atoms has the solubility in water and an organic solvent, and solubility suitable for the objective purposes can be imparted by reacting with a carboxyl group thereby introducing various atomic groups.
Among the bipyrrolinonylidene-type compounds represented by the general formula (1) used in the present invention, a metal salt or ester of the compound in which R1 and R2 are hydrogen atoms will now be described.
With respect to the bipyrrolinonylidene-type compound represented by the general formula (1) used in the present invention, either or both of two carboxyl groups may form a salt with a metal atom, while the solubility of the metal salt formed is drastically influenced by the kind of the metal atom. When the metal atom is an alkali metal such as sodium or potassium, the metal salt is soluble in water. When the metal salt is a polyvalent metal such as calcium, barium, aluminum or strontium, the metal salt is insoluble in water. When using the colorant of the present invention as a pigment for printing ink, the colorant is preferably insoluble in water and a polyvalent metal salt such as calcium or aluminum is preferably used.
With respect to the bipyrrolinonylidene-type compound represented by the general formula (1) used in the present invention, either or both of two carboxyl groups may form an ester. Examples of the ester include esters with an aliphatic monohydric alcohol, such as a methyl ester, ethyl ester, n-propyl ester, n-butyl ester, i-butyl ester, n-hexyl ester, n-octyl ester, n-decyl ester or n-octadecyl ester; esters with aliphatic polyhydric alcohols, such as a 2-hydroxyethyl ester, 2,3-dihydroxypropyl ester, 4-hydroxybutyl ester or 6-hydroxyhexyl ester; and esters with unsaturated alcohols, such as a benzyl ester, allyl ester, 2-(methacryloyl)-ethyl ester or 2-(tetrahydropyranyloxy)-ethyl ester. Among these, an ester with an aliphatic alcohol is preferred in view of high chemical stability of the ester group.
The bipyrrolinonylidene-type compound used in the present invention has a vivid color hue in a color ranging from blue to violet because of the chemical structure of the aryl groups Ar1 and Ar2, the kind of a metal atom which forms a salt, or the chemical structure of an ester and, therefore, it can be widely used, as a colorant, in fiber colorants, printing inks, color filters, automotive coating compositions, and plastic colorants. The bipyrrolinonylidenedicarboxylic acid derivative (A) in the present invention itself has a sufficient tinting power, but toning can be conducted by mixing with other colorants.
The bipyrrolinonylidene-type compound used in the present invention is obtained by oxidizing the pyrrolinone-type compound represented by the general formula (3). In the present invention, the bipyrrolinonylidene-type compound represented by the general formula (4) can be produced by oxidizing the pyrrolinone-type compound represented by the general formula (3) in the presence of an anthraquinone-type catalyst.
By the method of producing a bipyrrolinonylidene-type compound of the present invention, the bipyrrolinonylidene-type compound represented by the general formula (1) can be produced using, as a starting material, the pyrrolinone-type compound of the general formula (3) in which R is a carboxyl group or an alkoxycarbonyl group having 1 to 18 carbon atoms.
In the general formula (3) and the general formula (4), examples of the aryl group represented by Ar3 include groups having an aromatic ring, such as benzene, naphthalene, anthracene, phenanthrene, pyrene or biphenyl; and groups having an aromatic hetero ring, such as pyrrole, pyrazole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, carbazole, furan or thiazole. The fewer the aromatic rings or aromatic hetero rings in the aryl group, the higher the solubility of the resulting bipyrrolinonylidene-type compound in an organic solvent. The aryl group may have a substituent. Examples of the substituent include a halogen atom, cyano group, hydroxyl group, alkyl group, amino group, alkylamino group, alkoxyl group, aryl group, alkoxycarbonyl group, cycloalkyloxycarbonyl group, carbamoyl group, nitro group, sulfonic acid group and sulfonate group. When the substituent is a halogen atom, the resulting compound tends to exhibit higher chemical stability. When the substituent is a sulfonic acid group which may form a salt with a metal atom, the resulting bipyrrolinonylidene-type compound tends to exhibit higher solubility in water or organic solvents.
In the general formula (3) and the general formula (4), R represents a halogen atom, a cyano group, a hydroxy group, an amino group which may be substituted with an alkyl group, an alkoxy group, a cycloalkyloxy group, an alkyl group, a cycloalkyl group, an aryl group, an alkoxycarbonyl group, a cycloalkyloxycarbonyl group, a carbamoyl group, a nitro group, a carboxyl group which may form a salt with a metal atom, or a sulfonic acid group which may form a salt with a metal atom. When the substituent is a cyano group, an alkyl group, an aryl group, an alkoxycarbonyl group, or a carboxyl group which may form a salt with a metal atom, the resulting bipyrrolinonylidene-type compound tends to exhibit higher chemical stability.
In the method of producing the bipyrrolinonylidene-type compound of the present invention, examples of the anthraquinone-type catalyst include sodium anthraquinone-xcex2-sulfonate and sodium anthraquinone-xcex2,xcex2xe2x80x2-disulfonate. The amount of the anthraquinone-type catalyst is preferably used in an amount within a range from 1 to 50 mol %, and more preferably from 2 to 30 mol %, based on the pyrrolinone-type compound represented by the general formula (3).
In the oxidizing reaction of the pyrrolinone-type compound represented by the general formula (3), a solvent is preferably used. Examples of usable solvents include solvents which are less likely to be oxidized in the presence of the anthraquinone-type catalyst, for example, aromatic solvents such as nitrobenzene, toluene and xylene; alcohols such as methanol, ethanol, isopropanol, isobutanol and ethylene glycol monobutyl ether; esters such as ethyl acetate, butyl acetate and 2-etoxyethyl acetate; aprotic polar solvents such as N-methylpyrrolidone; and water and a mixed solvent of water and a water-soluble organic solvent. Among these solvents, nitrobenzene having a high ability of dissolving the pyrrolinone-type compound represented by the general formula (3), or a mixed solvent of nitrobenzene and the other organic solvent is preferred because high yield is achieved.
In the present invention, various oxidizing agents can be used. Specific examples thereof include peroxides such as hydrogen peroxide, m-chloroperbenzoic acid, peracetic acid, perchloric acid or potassium permanganate, or oxygen or air. When using air, there can he obtained such an advantage that high safety is achieved and manufacturing cost can be reduced. In the oxidizing reaction using air as an oxidizing agent, an inert gas such as nitrogen may be mixed with the air for the purpose of raising a lower limit of the explosive limit concentration of the reaction system.
In the oxidizing reaction, the reaction system may be heated for the purpose of increasing the reaction rate and the reaction system is preferably stirred for the purpose of allowing the oxidizing reaction to proceed uniformly. In the case of the oxidizing reaction using air as an oxidizing agent, the reaction temperature is controlled within a range from 100 to 250xc2x0 C., preferably from 140 to 230xc2x0 C., and more preferably from 170 to 210xc2x0 C., and air is preferably supplied uniformly into the reaction system after stirring sufficiently.
The bipyrrolinonylidene-type compound represented by the general formula (1) used in the present invention can be produced by the method of producing the bipyrrolinonylidene-type compound represented by the general formula (4) using the pyrrolinonylidene-type compound represented by the general formula (3).